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rdf:type |
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lifeskim:mentions |
umls-concept:C0034693,
umls-concept:C0034721,
umls-concept:C0035820,
umls-concept:C0205409,
umls-concept:C0225860,
umls-concept:C0871261,
umls-concept:C1446409,
umls-concept:C1704632,
umls-concept:C1706817,
umls-concept:C2003941,
umls-concept:C2911692
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pubmed:issue |
5
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pubmed:dateCreated |
1995-3-30
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pubmed:abstractText |
We determined the distribution of alpha 1A- and alpha 1B-adrenoceptor subtypes and their functional roles in phenylephrine (PE)-induced positive inotropic responses in rat atrium. Radioligand binding assays in membrane preparations of rat atria showed that 62% of [125I]BE 2254 binding sites were irreversibly inactivated by pretreatment with 20 microM chloroethylclonidine (CEC). Inhibition curves for WB 4101 and 5-methyl-urapidil (5-MU) were better fit by a two-site model, comprising 29-35% high-affinity sites and 65-71% low-affinity sites, suggesting that rat atria contains both alpha 1A and alpha 1B subtypes in a ratio of approximately 1:2. In isolated perfused atria, pretreatment with CEC inhibited the maximum PE-induced positive inotropic response by 55%, and pA2 values for WB 4101 and 5-MU in inhibiting this response were 8.26 +/- 0.4 and 7.85 +/- 0.07, respectively, between the KD values for alpha 1A and alpha 1B subtypes. PE shifted the concentration-contractile response curve for Ca2+ to the left and upward. Pretreatment with CEC completely abolished whereas 1 nM WB 4101 did not alter, the effect of PE on Ca2+ sensitivity. These results demonstrate that both alpha 1A- and alpha 1B- adrenoceptor subtypes are involved in the PE-induced positive inotropic response. Only activation of the alpha 1B subtype potentiates the positive inotropic effect induced by increasing extracellular Ca2+, however, which suggests that the mechanisms involved in the action of the two subtypes may differ at least in part.
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/(2-(2',6'-dimethoxy)phenoxyethylamin...,
http://linkedlifedata.com/resource/pubmed/chemical/5-methylurapidil,
http://linkedlifedata.com/resource/pubmed/chemical/Adrenergic alpha-Antagonists,
http://linkedlifedata.com/resource/pubmed/chemical/BE 2254,
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Clonidine,
http://linkedlifedata.com/resource/pubmed/chemical/Dioxanes,
http://linkedlifedata.com/resource/pubmed/chemical/Inositol Phosphates,
http://linkedlifedata.com/resource/pubmed/chemical/Phenethylamines,
http://linkedlifedata.com/resource/pubmed/chemical/Phenylephrine,
http://linkedlifedata.com/resource/pubmed/chemical/Piperazines,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Adrenergic, alpha-1,
http://linkedlifedata.com/resource/pubmed/chemical/Receptors, Adrenergic, alpha-2,
http://linkedlifedata.com/resource/pubmed/chemical/Tetralones,
http://linkedlifedata.com/resource/pubmed/chemical/chlorethylclonidine
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pubmed:status |
MEDLINE
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pubmed:month |
Nov
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pubmed:issn |
0160-2446
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
24
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
745-52
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pubmed:dateRevised |
2007-7-11
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pubmed:meshHeading |
pubmed-meshheading:7532752-Adrenergic alpha-Antagonists,
pubmed-meshheading:7532752-Animals,
pubmed-meshheading:7532752-Atrial Function,
pubmed-meshheading:7532752-Binding, Competitive,
pubmed-meshheading:7532752-Calcium,
pubmed-meshheading:7532752-Clonidine,
pubmed-meshheading:7532752-Dioxanes,
pubmed-meshheading:7532752-Dose-Response Relationship, Drug,
pubmed-meshheading:7532752-Heart Atria,
pubmed-meshheading:7532752-Inositol Phosphates,
pubmed-meshheading:7532752-Male,
pubmed-meshheading:7532752-Myocardial Contraction,
pubmed-meshheading:7532752-Phenethylamines,
pubmed-meshheading:7532752-Phenylephrine,
pubmed-meshheading:7532752-Piperazines,
pubmed-meshheading:7532752-Radioligand Assay,
pubmed-meshheading:7532752-Rats,
pubmed-meshheading:7532752-Rats, Wistar,
pubmed-meshheading:7532752-Receptors, Adrenergic, alpha-1,
pubmed-meshheading:7532752-Receptors, Adrenergic, alpha-2,
pubmed-meshheading:7532752-Tetralones
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pubmed:year |
1994
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pubmed:articleTitle |
Role of alpha 1A- and alpha 1B-adrenoceptors in phenylephrine-induced positive inotropic response in isolated rat left atrium.
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pubmed:affiliation |
Institute of Vascular Medicine, Third Hospital, Beijing Medical University, China.
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pubmed:publicationType |
Journal Article,
In Vitro,
Research Support, Non-U.S. Gov't
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